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PINE BEETLE. 
117 
or (very notably) the choppings of wood with bark on, which are too 
often left lying about where plantations have been thinned and the 
poles dressed on the spot. In these, and in similar situations, where 
there is still sap present, but it is not in sufficient flow to fill the 
galleries, the beetle makes its breeding tunnels, and the maggots 
develop to maturity. Therefore removal of all such nurseries, or 
placing pieces of wood with bark attached to attract the beetles, and 
clearing away these and destroying them, are amongst the best methods 
of preventing mischief from this attack to the live Pine shoots. 
Excepting where the tunnelling beneath the bark for breeding pur¬ 
poses accelerates the destruction of an already unhealthy tree, this 
part of the infestation is rarely seriously injurious. It is the boring of 
the beetles up the centre of the Pine shoots which is the great cause 
of damage.* 
What has been the cause of this heretofore (so far as we are aware) 
unknown occurrence of attack of H. piniperda to Larch in Scotland, we 
cannot be absolutely sure of. It will be seen, in the following extract, 
that Dr. Somerville attributes it to the enormous quantity of forest 
insects which, from special circumstances, were for a while present in 
the South of Scotland :— 
“ As to the cause of H. pimperda attacking the Larch, I believe a 
satisfactory reason can be given. About ten years ago the southern 
counties of Scotland were visited by a succession of exceptionally 
severe gales, which overturned enormous numbers of Pines and other 
trees. Partly owing to the glutted state of the market, and partly to 
the difficulty experienced in dealing with such a large amount of fallen 
timber, the woods were allowed to remain undisturbed in their devas¬ 
tated condition for a number of years. These dead and dying trees 
furnished an exceptionally favourable breeding place for H. piniperda, 
which consequently increased at a prodigious rate, each average sized 
Pine being capable of producing, it is said, as many as 80,000 insects. 
Within the past year or two the last of this fallen timber has been re¬ 
moved, with the result that the huge army of forest insects, by which the 
country is over-run, cannot be accommodated with the breeding places 
which they prefer, and have therefore been compelled to oviposit on 
what they must consider most unsuitable material. 
“ Thus, owing to stress of circumstances, H. piniperda has been 
driven to attack the Larch, and in this country I have also found Scots 
Pines, not exceeding eight years of age, infested by it, although hitherto 
trees of a less age than fifteen years have seldom been known to be 
attacked.” t 
* Observations on methods of prevention and remedy, mainly contributed by 
♦ Scottish Head Foresters, have been given in previous Reports, and in my ‘ Manual 
of Injurious Insects.’— Ed. 
f See paper by Dr. Somerville previously quoted. 
